I have always been of the opinion that I don't care why someone is homeless, I would like to help them. There is nobody that deserves to live on the street in a nation with as much wealth as America, even if they've made bad decisions (drugs, alcohol, crime, etc.). I think it's our job as a society to put a roof over everyone's head to the best of our abilities, it's inhuman to pick and dodge among homeless people and go about our lives like it is normal.
If I could solve any problem in my lifetime, it would be homelessness in America. I wish I had any idea where to start. I know it's not as noble of a cause as curing cancer or helping the needy who live in true poverty around the world, but it's something that's in my face every day and I think it's a failure of our modern society.